Ventilation For a Portable Electronic Device

ABSTRACT

A portable electronic device comprising a casing ( 5 ); a speaker ( 20 ) mounted adjacent an orifice ( 10 ) of the casing ( 5 ); an air permeable membrane ( 25 ) sealingly mounted to the cading ( 5 ) intermediate the orifice ( 10 ) and the speaker ( 20 ), so as to form a chamber ( 35 ) between the speaker ( 20 ) and the membrane ( 25 ); wherein the membrane ( 25 ) permits the ingress and egress of air ( 30 ), into the casing ( 5 ) through the orifice ( 10 ).

FIELD OF THE INVENTION

The invention relates to portable electronic devices, such as PDA's, andin particular those used for industrial applications. Specifically, theinvention relates to means for adjusting the casing of such a device forenhanced performance, and specifically for ventilation of the casing.

BACKGROUND

For electronic devices, the internal components generate a considerableamount of heat, which must be dissipated. Whilst desk-top applicationscan incorporate fans to provide a flow of air through the internalcomponentry, such a flow of air is not available to smaller electronicdevices particularly those which are considered portable, as theincorporation of a fan is impractical.

However, such smaller electronic devices may not require a considerableflow of air in order to dissipate heat because of the comparativelysmall amount of heat generated or intermittent use as compared to themore continual use of electronic devices normally used in commercialenvironments.

Thus, portable electronic devices can usually suffice with having ventswithin the casing to allow heated air to dissipate out of the device.

A special class of such portable electronic devices are those used inindustrial applications, as distinct from similar commercial deviceswhich are not sufficiently protected from the adverse environmentsexperienced for industrial applications. For instance, dust, dirt,moisture etc. can seriously affect the practical and commercial life ofa device. Commercial devices are not designed to resist such adverseenvironmental considerations and therefore may not have a sufficientlylong effective life to warrant the cost of having such devices in anindustrial environment. Therefore, portable electronic devices geared toindustrial applications will at least seek to have protection againstthe ingress of dirt, dust and moisture, which inter alia arepredisposing causes to the failure of such devices.

Thus, the problem of dissipating heated air from a device adapted forindustrial use presents a particularly difficult issue. Because saiddevices are protected from the ingress of undesirable materials, saiddevices are frequently air and water tight. Consequently, not only doessuch a portable electronic device have no fan to help dissipate theheated air, in fact, the heated air cannot escape from the deviceitself.

Consequently, it is known for such devices to explode due to pressureand heat build-up causing both a shortened life of the device andpossibly a safety hazard.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to avoid the build-upof such heated air for a device adapted for industrial use.

In a first aspect, the invention provides a portable electronic devicecomprising a casing;

a speaker mounted adjacent an orifice of the casing;

an air permeable membrane mounted to the casing intermediate the orificeand the speaker, so as to form a chamber between the speaker and themembrane, wherein;

the membrane prevents ingress of water, but permits the ingress andegress of air, into the casing through the orifice.

Thus, by providing a seal in the casing of the device that permits thefree flow of air but prevents the ingress of water, the portableelectronic device is protected from damaging ingress of materials, butallows for the venting of hot air from the device thus avoiding saiddevice from exploding.

The invention has the further advantage in that by providing ventilationof the hot air at the point of the speaker, extra ventilation points arenot required. On the basis that the chance of moisture penetrating thecasing is increased in proportion to the number of openings in thecasing by combining the purpose of the orifice for a speaker and aventilation port, the double use of the orifice halves the number ofopportunities through which water can penetrate the casing.

Further, the size of a speaker in such a device may be proportionallylarge within such a device. Thus, by providing a combined ventilationport and speaker, the area through which air may vent may be larger andthus provide much higher capacity for the venting of hot air than wouldnormally be provided through smaller, conventional venting holes.

In a preferred embodiment, the advantage of combining the speakerorifice with the vent port provides the opportunity to structure thearrangement so as to provide a protected sound chamber for the speaker.Thus, in this preferred embodiment by forming a chamber between themembrane and the speaker, so as to be of sufficient size may enhance theaudio quality of the speaker and so increase the performance of theelectronic device whilst also providing a means through which hot airmay be ventilated.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows an isometric view of the portable electronic deviceaccording to one embodiment of the present invention;

FIG. 2 shows a sectional view of the speaker according to the embodimentof FIG. 1.

It will be convenient to further describe the present invention withrespect to the accompanying drawings, which illustrate a possiblearrangement of the invention. Other arrangements of the invention arepossible and consequently the particularity of the accompanying drawingsis not to be understood as superceding the generality of the precedingdescription of the invention.

DESCRIPTION OF PREFERRED EMBODIMENT

FIG. 1 shows one embodiment of the present invention, in particular, acasing of a portable electronic device has been removed so as to examinethe internal componentry. In particular, this view shows a circularorifice 10 has been moulded into the casing 5 so as to fit a speaker 20.The orifice 10 includes a covering with holes 15 placed in it such thatanything passing through the orifice 10 must also pass through the holes15. Further shown in this view is a membrane 25 which, in the explodedview of FIG. 1, is placed intermediate the orifice 10 and the speaker20.

FIG. 2 shows a detailed cross-sectional view of the assembly associatedwith the orifice 10.

It will be seen that adjacent the orifice 10 is a recess 40 having astep 45 into which the speaker 20 will fit ready for mounting within thecasing 5, either glued or otherwise fixed to the casing 5. Abutting theorifice 10 is a membrane 25 of a suitable material which is bothwaterproof and permeable to air. A suitable material may be TEMISH™ filmfrom Nitto Denko. This material is merely one such suitable material,and in no way limits the invention to this material. It will be clear tothe skilled addressee that many such materials could be used also, andstill fall within the scope of the invention, without undueexperimentation. The membrane 25 is glued to the casing 5, so as tocompletely cover and seal the orifice 10. An alternative arrangement mayhave the membrane 25 merely covering the holes 15, which would reducethe material required but substantially increase the manufacturingcosts. Whilst this embodiment shows the membrane 25 abutting the orifice10, an alternative arrangement may have the membrane 25 sealing therecess 40 into which the speaker has been mounted. Whilst this maypermit the build-up of detritus within the chamber 35, the membranewould permit the sealing of the electronic device whilst also permittingthe flow of air.

In a further preferred embodiment, having the membrane 25 abutting theorifice 10, forms a chamber 35 in an interstitial space between themembrane 25 and the speaker 20. The placement of this chamber 35 permitsit to act as a sound chamber for the speaker and so considerablyincrease the performance of the speaker whilst still satisfying theobjectives of the invention.

A major consideration for the invention is the ability of heated air 30to escape from the electronic device so as to prevent the deviceexploding. By securing the speaker 20 into the recess 40 in a mannerthat still permits the flow of air, then the heated air can enter thechamber 35 and pass through the membrane 25 and so escape to theatmosphere. Thus, the air permeable/waterproof membrane 25 serves thedual function of protecting the device from the ingress of water whilstalso permitting the egress of hot air into the atmosphere through theorifice 10.

1. A portable electronic device comprising: a casing; a speaker mountedadjacent an orifice of the casing; an air permeable membrane sealinglymounted to the casing intermediate the orifice and the speaker, so as toform a chamber between the speaker and the membrane; and wherein themembrane permits the ingress and egress of air, into the casing throughthe orifice.
 2. The device according to claim 1, wherein said membraneis waterproof and mounted such that water ingress through the orifice isprevented.
 3. The device according to claim 1, wherein the passage ofair and water is only permitted into the casing through the orifice,said passage of water prevented by the mounted membrane.
 4. The deviceaccording to claim 1, wherein the orifice comprises a plurality of holesin a portion of the casing.
 5. The device according to claim 1, whereinthe chamber acts as a sound chamber for the speaker.